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Observations of Environmental Thermoregulation by Chicks
Observations of Environmental Thermoregulation by Chicks W. D. MORRISON Department of Animal and Poultry Science, University of Guelph, Guelph, Ontario, Canada, NIG 2W1 S. E. CURTIS Department of Animal Science, University of Illinois, Urbana, Illinois 61801 (Received for publication February 3, 1983)
1983 Poultry Science 62:1912-1914 INTRODUCTION
Numerous papers have been published concerning operant conditioning of chickens (Fischer, 1975); many relate to the chickens learning to activate a swith to obtain food or heat. Baldwin and Ingram (1968) and Curtis and Morris (1982) have shown that young pigs housed in groups show a diurnal rhythm for heat demand; the young pigs allowed the room temperature, to drop markedly during the night without activating a switch to provide heat. The purpose of the trials reported herein was to determine if such a diurnal rhythm exists for young chicks housed in a moderately cool environment.
was recorded on a Simpson recorder (Model 2755). The infrared bulb remained on for either 2 or 3 min, and during that time the temperature at floor level reached 33 C. Chicks were housed in groups of two, four, or eight either on wire or on litter for a period of 7 days. Food and water were provided ad libitum. Light was provided 24 hr per day. Six experiments were conducted following initial trials to adapt equipment. One experiment utilized four birds in the chamber and a 2-min heat reward, one used two chicks and a 3-min reward, two used eight chicks and a 3-min reward, and two used eight chicks and a 3-min reward with the chicks housed on litter rather than wire.
MATERIALS AND METHODS New Hampshire X Columbian male chicks, 8 days of age, were placed in a 48 X 45-cm chamber with a microswitch located in one wall. The height of the 2-cm 2 activating button was dependent on the age of the chick, but initially its bottom was 8 cm from the floor. Room temperature was 20 C, and a fan stirred the air in the chamber continuously. Pecking the button activated an infrared 250 W bulb located 40 cm above the floor immediately above the microswitch button. Birds readily learned to press the microswitch without any assistance or reward other than the radiant heat from the infrared bulb. The number of strikes rewarded by heat as well as nonrewarded strikes
RESULTS AND DISCUSSION None of the trials revealed the marked diurnal rhythm found in pigs (Fig 1). There was some indication that the chicks provided themselves with 2 to 3 min more of heat per hour at night, but marked contrasts were not evident. The response may have differed if the chicks had received light and dark periods. Van Kampen et al. (1979) reported a reduction in the lower range of the thermoneutral zone of 7-week-old chicks housed in the dark. Rather than reducing heat demand, housing chicks in a group of eight instead of a group of two gave indication of increasing the amount of heat
1912
Downloaded from http://ps.oxfordjournals.org/ at Universite de Sherbrooke on April 11, 2015
ABSTRACT Chicks, 8 days of age, were housed at 20 C in a 48 X 45 cm chamber with a microswitch in one wall. Pressing the microswitch provided radiant heat from an infrared bulb located above the switch. Six experiments were conducted using from two to eight chicks per group. Heat was provided for 2 or 3 min. In two experiments chicks were on litter; in four experiments chicks were on wire floors. Chicks provided themselves with heat without difficulty and reduced heat demand when housed on litter rather than wire. Less total heat was provided with reward times of 2 min. No diurnal rhythm was evident. (Key words: chick, operant, thermoregulation)
RESEARCH NOTE
1913
TABLE 1. Response of chicks housed in different group sizes and with or without litter to a cool environment Treatment
1 2 3 4 5 6
Birds
Cycle length
Days
(no.)
(min)
(no.)
4 2 8 8 8 8
2 3 3 3 3 3
3 3 3 3 3 3
Floor
Heat1 (min/hr)
Wire Wire Wire Litter Litter Wire
20.58 24.21 27.58 22.38 23.13 28.71
FIG. 1. Minutes for all trials. Each mean of 3 hr; for is mean of 1, 2, and
of extra heat demanded by chicks figure on the abscissa represents example, height of line above 2 3.
Time-24 hour clock
20 23 •••Trial 1 - 4 birds • Trial 2 - 2 birds IIHHI Trials 3 and 6 - 8 birds xxx Trials 4 and 5 - 8 birds
FIG. 2. Minutes of extra heat demanded by chicks housed in groups of four, two, and eight.
12
to -
Time-24 hour clock
FIG. 3. Total strikes and strikes for heat only for all trials. Each figure on the abscissa represents mean of 3 hr; for example, height of line above 2 is mean of 1, 2, and 3.
1
Standard deviation 5.37.
demand (Table 1; Fig. 2). This is true despite the extra opportunity for huddling. Of course, the larger number of chicks also distributed the "work" over more birds and may have been a factor. There is no suggestion here that more birds reduce heat demand, as has been shown in pigs. The sensitivity of the chick to a more comfortable environment is demonstrated in the quite precise manner in which heat demand was reduced by chicks on litter. The difference between the means of eight birds on litter and eight birds on wire was significant at P<.05 using the test of least significant difference. For other comparisons among treatments a difference of 5.31 min is required for significance at P<.05 using Tukey's test (Steel and Torrie, 1960). Reward periods of 2 min duration resulted in reduced total heat demand. It seems chicks choose not to strike the button sufficiently often to offset the difference between the total heat provided by a 2- and 3-min reward. Chicks did strike the button on occasion when the heat was already on but this was not frequent. Strikes per hour (total and rewarded) are shown in Figure 3. Opportunity to conserve supplemental radiant energy due to diurnal operant heat demand does not appear feasible with week-old chicks housed at 20 C.
REFERENCES Baldwin, B. A., and D. L. Ingram, 1968. Factors influencing behavioral thermoregulation in the pig. Physiol. Behav. 3:409-415. Curtis, S. E., and G. L. Morris, 1982. Operant sup-
Downloaded from http://ps.oxfordjournals.org/ at Universite de Sherbrooke on April 11, 2015
Time-24 hour clock
1914
MORRISON AND CURTIS
plemental heat in swine nurseries. Pages 295—297 in Proc. 2nd Int. Livest. Environ. Symp. Am. Soc. Agric. Eng., Ames, IA. Fischer, G. F., 1975. The behaviour of chickens. The Behaviour of Domestic Animals. E.S.E. Hafez, ed. Williams and Wilkins Co., Baltimore, MD. Steel, R.G.D., and J. H. Torrie, 1960. Principles and Procedures of Statistics. McGraw Hill, New York,
NY. Van Kampen, M., B. W. Mitchell, and H. S. Siegel, 1979. Thermoneutral zone of chickens as determined by measuring heat production, respiration rate and electromyographic and electroencephalographic activity in light and dark environments and changing ambient temperatures. J. Agric. Sci. Camb 92:219-226.
Downloaded from http://ps.oxfordjournals.org/ at Universite de Sherbrooke on April 11, 2015
1983 Poultry Science 62:1912-1914 INTRODUCTION
Numerous papers have been published concerning operant conditioning of chickens (Fischer, 1975); many relate to the chickens learning to activate a swith to obtain food or heat. Baldwin and Ingram (1968) and Curtis and Morris (1982) have shown that young pigs housed in groups show a diurnal rhythm for heat demand; the young pigs allowed the room temperature, to drop markedly during the night without activating a switch to provide heat. The purpose of the trials reported herein was to determine if such a diurnal rhythm exists for young chicks housed in a moderately cool environment.
was recorded on a Simpson recorder (Model 2755). The infrared bulb remained on for either 2 or 3 min, and during that time the temperature at floor level reached 33 C. Chicks were housed in groups of two, four, or eight either on wire or on litter for a period of 7 days. Food and water were provided ad libitum. Light was provided 24 hr per day. Six experiments were conducted following initial trials to adapt equipment. One experiment utilized four birds in the chamber and a 2-min heat reward, one used two chicks and a 3-min reward, two used eight chicks and a 3-min reward, and two used eight chicks and a 3-min reward with the chicks housed on litter rather than wire.
MATERIALS AND METHODS New Hampshire X Columbian male chicks, 8 days of age, were placed in a 48 X 45-cm chamber with a microswitch located in one wall. The height of the 2-cm 2 activating button was dependent on the age of the chick, but initially its bottom was 8 cm from the floor. Room temperature was 20 C, and a fan stirred the air in the chamber continuously. Pecking the button activated an infrared 250 W bulb located 40 cm above the floor immediately above the microswitch button. Birds readily learned to press the microswitch without any assistance or reward other than the radiant heat from the infrared bulb. The number of strikes rewarded by heat as well as nonrewarded strikes
RESULTS AND DISCUSSION None of the trials revealed the marked diurnal rhythm found in pigs (Fig 1). There was some indication that the chicks provided themselves with 2 to 3 min more of heat per hour at night, but marked contrasts were not evident. The response may have differed if the chicks had received light and dark periods. Van Kampen et al. (1979) reported a reduction in the lower range of the thermoneutral zone of 7-week-old chicks housed in the dark. Rather than reducing heat demand, housing chicks in a group of eight instead of a group of two gave indication of increasing the amount of heat
1912
Downloaded from http://ps.oxfordjournals.org/ at Universite de Sherbrooke on April 11, 2015
ABSTRACT Chicks, 8 days of age, were housed at 20 C in a 48 X 45 cm chamber with a microswitch in one wall. Pressing the microswitch provided radiant heat from an infrared bulb located above the switch. Six experiments were conducted using from two to eight chicks per group. Heat was provided for 2 or 3 min. In two experiments chicks were on litter; in four experiments chicks were on wire floors. Chicks provided themselves with heat without difficulty and reduced heat demand when housed on litter rather than wire. Less total heat was provided with reward times of 2 min. No diurnal rhythm was evident. (Key words: chick, operant, thermoregulation)
RESEARCH NOTE
1913
TABLE 1. Response of chicks housed in different group sizes and with or without litter to a cool environment Treatment
1 2 3 4 5 6
Birds
Cycle length
Days
(no.)
(min)
(no.)
4 2 8 8 8 8
2 3 3 3 3 3
3 3 3 3 3 3
Floor
Heat1 (min/hr)
Wire Wire Wire Litter Litter Wire
20.58 24.21 27.58 22.38 23.13 28.71
FIG. 1. Minutes for all trials. Each mean of 3 hr; for is mean of 1, 2, and
of extra heat demanded by chicks figure on the abscissa represents example, height of line above 2 3.
Time-24 hour clock
20 23 •••Trial 1 - 4 birds • Trial 2 - 2 birds IIHHI Trials 3 and 6 - 8 birds xxx Trials 4 and 5 - 8 birds
FIG. 2. Minutes of extra heat demanded by chicks housed in groups of four, two, and eight.
12
to -
Time-24 hour clock
FIG. 3. Total strikes and strikes for heat only for all trials. Each figure on the abscissa represents mean of 3 hr; for example, height of line above 2 is mean of 1, 2, and 3.
1
Standard deviation 5.37.
demand (Table 1; Fig. 2). This is true despite the extra opportunity for huddling. Of course, the larger number of chicks also distributed the "work" over more birds and may have been a factor. There is no suggestion here that more birds reduce heat demand, as has been shown in pigs. The sensitivity of the chick to a more comfortable environment is demonstrated in the quite precise manner in which heat demand was reduced by chicks on litter. The difference between the means of eight birds on litter and eight birds on wire was significant at P<.05 using the test of least significant difference. For other comparisons among treatments a difference of 5.31 min is required for significance at P<.05 using Tukey's test (Steel and Torrie, 1960). Reward periods of 2 min duration resulted in reduced total heat demand. It seems chicks choose not to strike the button sufficiently often to offset the difference between the total heat provided by a 2- and 3-min reward. Chicks did strike the button on occasion when the heat was already on but this was not frequent. Strikes per hour (total and rewarded) are shown in Figure 3. Opportunity to conserve supplemental radiant energy due to diurnal operant heat demand does not appear feasible with week-old chicks housed at 20 C.
REFERENCES Baldwin, B. A., and D. L. Ingram, 1968. Factors influencing behavioral thermoregulation in the pig. Physiol. Behav. 3:409-415. Curtis, S. E., and G. L. Morris, 1982. Operant sup-
Downloaded from http://ps.oxfordjournals.org/ at Universite de Sherbrooke on April 11, 2015
Time-24 hour clock
1914
MORRISON AND CURTIS
plemental heat in swine nurseries. Pages 295—297 in Proc. 2nd Int. Livest. Environ. Symp. Am. Soc. Agric. Eng., Ames, IA. Fischer, G. F., 1975. The behaviour of chickens. The Behaviour of Domestic Animals. E.S.E. Hafez, ed. Williams and Wilkins Co., Baltimore, MD. Steel, R.G.D., and J. H. Torrie, 1960. Principles and Procedures of Statistics. McGraw Hill, New York,
NY. Van Kampen, M., B. W. Mitchell, and H. S. Siegel, 1979. Thermoneutral zone of chickens as determined by measuring heat production, respiration rate and electromyographic and electroencephalographic activity in light and dark environments and changing ambient temperatures. J. Agric. Sci. Camb 92:219-226.
Downloaded from http://ps.oxfordjournals.org/ at Universite de Sherbrooke on April 11, 2015